Syringe Assembly

ABSTRACT

A syringe assembly comprises a syringe barrel having an elongated body defining a chamber for retaining fluid, an open proximal end, a distal end and a frusto-conically shaped tip extending from the distal end and having a passageway therethrough in fluid communication with the chamber. The chamber has an inside diameter of at least 13.5 mm. A stopper is in fluid-tight engagement inside the barrel. An elongated plunger rod extends proximally from the stopper through the open proximal end of the barrel. A flange is positioned at the proximal end of the plunger rod. The flange is shaped and positioned to limit the distal motion of the plunger rod in the barrel by contacting the proximal end of the barrel. A tip cap is releasably connected to the tip for sealing the passageway and the chamber contains injectable liquid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/684,189,filed on Jan. 8, 2010, which is a division of U.S. patent applicationSer. No. 10/727,194, filed on Dec. 3, 2003, now U.S. Pat. No. 7,682,342,issued Mar. 23, 2010, which is a continuation of U.S. patent applicationSer. No. 10/067,166, filed on Feb. 4, 2002, now abandoned, which is acontinuation of U.S. patent application Ser. No. 09/060,117, filed onApr. 14, 1998, now U.S. Pat. No. 6,361,524, issued Mar. 26, 2002.

BACKGROUND OF THE INVENTION

The present invention relates to syringe assemblies and moreparticularly concerns syringe assemblies for use in I.V. flushprocedures.

An I.V. catheter is a commonly used therapeutic device. Many patients,in accordance with their therapy, have an I.V. catheter connected to avein ready for use in various procedures or in fluid communication withan I.V. system for infusing liquids and medication. Many I.V. sets haveI.V. ports which are in fluid communication with a catheter and allowaccess for the purpose of injecting medication into the patient, and foruse in flushing techniques to maintain catheter patency and integrity.Healthcare facilities have flushing protocols which depend on the amountof time the catheter will remain in the patient and the type of catheterbeing used. For example, a peripherally inserted central catheter (PICC)is a long flexible catheter, which is typically inserted into thecentral venous system (optimally with the tip terminating in thesuperior vena cava) via the superficial veins of the antecubital fossa.PICC lines are designed for use when intermediate or long-term therapyis prescribed. These catheter lines must be periodically flushed withsaline flush solution and/or heparin lock flush solution depending onthe protocol. Among other things, flushing saline solution removes bloodfrom the catheter and heparin helps prevent the formation of futureblood clots. The most common I.V. ports are covered by pierceableseptums or pre-slit septums and are known in the art and sometimesreferred to as “PRN” from the Latin pro re nata meaning “as the needarises”. The septum is preferably made of rubber or another elastomericmaterial which permits insertion of a sharp needle cannula in order toinfuse fluids into or to withdraw fluids from the catheter. Uponwithdrawal of the needle cannula the septum seals itself. Ports havingpre-slit septums are used with blunt cannula. Typically, the bluntcannula is attached to a syringe and the syringe is moved to place agentle pressure on the pre-slit septum which is forced open by the bluntcannula to establish fluid communication. Also, some I.V. sets haveaccess valves which are responsive to the frusto-conically shaped tip ofa syringe barrel for allowing fluid communication between the interiorof the syringe and the catheter.

Catheters are flushed using syringe assemblies filled with variousfluids. In some cases, different fluids are injected sequentially inaccordance with the protocol. For example, a saline solution followed byan anticoagulant such as heparin. The size of the syringe used to flushI.V. lines varies by various factors including the size and length ofthe catheter. Typically syringes of 1 ml, 3 ml, 5 ml and 10 ml volumeare used. A commercially available 1 ml syringe may have a barrel insidediameter of approximately 6.6 mm (0.26 inch), a 3 ml syringe may have abarrel inside diameter of approximately 8.6 mm (0.34) inch while a 10 mlsyringe may have a barrel inside diameter of approximately 14.5 mm (0.57inch). Unfortunately, during the flushing of vascular access devices,different nominal size syringes generate substantially differentpressures in the solution being injected by the same force being appliedto the syringe plunger rod. For example, a ten-pound force on theplunger rod may cause a 10 ml syringe to generate 40 psi of liquidpressure while a 3 ml syringe generates 110 psi and a 1 ml syringegenerates 190 psi.

Control of pressure is very important during flush procedures fordetection of resistance to flow or catheter occlusion, and to avoidover-pressure because of the danger of dislodging a clot or rupturingthe catheter. Accordingly, many practitioners are believed to prefer the10 ml size syringe because when using the 10 ml syringe it is easier toobserve possible catheter occlusion and it is less likely to provideexcessive pressures which could dislodge a blood clot or damage thecatheter.

Also, it is important in the flush procedure not to draw blood back intothe catheter where it can clot and seal the catheter. In order toprevent blood reflux into the catheter the user is encouraged tomaintain a positive pressure in the line during the flush procedure.This may involve slowly withdrawing the syringe and cannula from theI.V. port while still applying pressure to the syringe plunger rod. Whenusing a syringe with an elastomeric stopper, if the stopper iscompressed by action of the plunger rod, release of the plunger rodcauses the stopper to expand and may cause blood to enter the catheterline.

Although a wide variety of catheters and I.V. ports can be adequatelyflushed using currently available syringe assemblies, there is still aneed for simple, straight forward easy-to-manufacture syringe assemblieswhich eliminate the substantial pressure variations possible with thepresent syringes and minimize the potential for accidentally drawingblood in the catheter during the flush procedure.

SUMMARY OF THE INVENTION

A syringe assembly comprises a syringe barrel having an elongated bodydefining a chamber for retaining fluid, an open proximal end, a distalend and a frusto-conically shaped tip extending from the distal endhaving a tip passageway therethrough in fluid communication with thechamber. The chamber has an inside diameter of at least 13.5 mm (0.53inch). The chamber has a distal end defined by a distal wall throughwhich the passageway passes. A stopper is in fluid communication withthe inside of the barrel. An elongated rigid plunger rod extendsproximally from the stopper through the open proximal end of the barreland contains a flange at its proximal end. The flange is shaped andpositioned to limit the distal motion of the plunger rod in the barrelby contacting the proximal end of the barrel. A tip cap is releasablyconnected to the tip for sealing the passageway and the chamber containsinjectable liquid.

In another embodiment the stopper and the plunger rod are dimensioned sothat when the plunger rod flange contacts the proximal end of the barrelthere is a space between at least a portion of the distal end of thestopper and the distal wall of the syringe barrel.

In another embodiment, a syringe assembly comprises a syringe barrelhaving an elongated body defining a chamber for retaining fluid, an openproximal end, a distal end and a frusto-conically shaped tip extendingfrom the distal end and having a tip passageway therethrough in fluidcommunication with the chamber. The chamber has an inside diameter of atleast about 13.5 mm (0.53 inch). The chamber has a distal end defined bya distal wall through which the passageway passes. The length of thechamber is no more than about 57 mm (2.25 inches). A stopper is influid-tight communication with the inside of the barrel. An elongatedplunger rod extends proximally from the stopper through the openproximal end of the barrel. In this embodiment the plunger rod does notnecessarily have a flange on its proximal end, and the plunger rodflange does not necessarily limit the distal motion of the plunger rodin the barrel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view illustrating a prior art syringe assembly andneedle assembly.

FIG. 2 illustrates a prior art syringe and needle assembly being used toflush an I.V. site and catheter.

FIG. 3 illustrates the prior art syringe of FIG. 1 with the plunger rodand stopper in their most proximal position simulating a syringe full ofliquid for injection.

FIG. 4 illustrates the syringe assembly of the present invention.

FIG. 5 is en enlarged partially cross-sectioned view of the syringeassembly of FIG. 4.

FIG. 6 illustrates the syringe assembly of FIG. 4 being used to flush anI.V. site and catheter.

FIG. 7 is an enlarged cross-sectional view of the syringe assembly ofthe present invention illustrating the syringe assembly after use.

FIG. 8 illustrates a family of syringes of the present invention havingthree volumes of 3 ml, 5 ml and 10 ml.

FIG. 9 illustrates a kit containing two syringe assemblies of thepresent invention in a package which acts as a sterile barrier.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is satisfied by embodiments in many differentforms, there are shown in the drawings and will herein be described indetail, preferred embodiments of the invention with the understandingthat the present disclosure is to be considered exemplary of theprinciples of the invention and not intended to limit the invention tothe embodiments illustrated. The scope of the invention will be measuredby the appended claims and their equivalents.

Adverting to FIGS. 1-7, prior art syringe assembly 20 includes a barrel21 having an elongate body 22 defining a chamber 23 for retaining fluid.The barrel includes an open proximal end 25 having a flange 26 and adistal end 27 including a tip 28 having a passageway 29 therethrough influid communication with the chamber. The distal end of the barrel alsopreferably, but not necessarily, includes a locking luer-type collar 30concentrically surrounding tip 28. The luer collar has an internalthread 33.

A prior art needle assembly includes a cannula 38 having a proximal end39, a distal end 40 and a lumen therethrough. The distal end of thecannula may include a sharp tip 43 or a blunt tip (not illustrated). Ahub 44 includes an open proximal end 45 containing a cavity and a distalend 47 attached to proximal end 39 of cannula 38 so that the lumen ofthe cannula is in fluid communication with the cavity in the hub. Theneedle assembly is attached to the syringe through frictional engagementof the interior surface of the cavity and the exterior surface of tip28. The hub also includes radial projections 42 on its proximal end forengaging thread 33 to hold it securely to the barrel. Prior art syringeassembly 20 further includes a resilient stopper 31 connected to anelongated plunger rod 32 having a flange 34 at its proximal end.

The most commonly used 3 ml syringe in the United States has a barrelinside diameter of approximately 8.6 mm (0.34 inch). As best illustratedin FIG. 1, the length of its plunger rod and stopper is longer than thechamber in the barrel so that portions of the plunger rod and theplunger rod flange extend proximally from the open proximal end of thebarrel when the stopper has reached its maximum distal position and isresting on the interior distal wall of the chamber. Further, the barrelflange is not non-circularly shaped while the plunger rod flange iscircularly shaped so that the plunger rod flange extends radially beyondthe outside of the barrel flange to facilitate drawing the plunger rodand stopper in a proximal direction to fill the syringe using knownmethods.

In use, the prior art 3 ml syringe assembly is connected to a hypodermicneedle assembly and filled with flush solution using known methods. Forexample, the syringe with needle assembly attached is used to pierce thepierceable stopper of a vial containing flush solution and the flushsolution is drawn into the syringe barrel by pulling plunger rod flange34 in a proximal direction while holding barrel 21, to draw fluidthrough the needle cannula into the chamber of the syringe barrel.

I.V. sets can be very complicated and include multiple injection ports,a valve and other components. For the purpose of illustrating thepresent invention a simplified I.V. set 48 is illustrated in FIG. 2.I.V. set 48 comprises an I.V. site 51 which includes a housing 50 havinga hollow interior conduit 52 and a septum 53 at its proximal end. Acatheter 49 having a lumen therethrough extends from the distal end ofthe housing.

The filled prior art syringe is now ready for use in flushing acatheter. With the embodiment illustrated, sharp tip 43 of cannula 38 ismoved to pierce septum 53 to establish fluid communication between thehollow interior conduit 52 of housing 51 and the chamber of the syringebarrel. The syringe is held so that the liquid in the chamber can beforced into the hollow interior conduit of the housing and through thecatheter by applying digital pressure, such as with the use of thethumb, to flange 34 to move the plunger rod in a distal direction withrespect to the barrel. Due to the relatively small diameter of thesyringe barrel the user must be careful not to exert excess pressurewhich could dislodge a blood clot or damage the catheter. Also, it isimportant to maintain a positive pressure during the flush procedure sothat when the syringe is nearly empty, the user should begin to withdrawthe cannula from the septum as the fluid is being expelled. The priorart syringe has a disadvantage when being used as a flush syringe sincethe length of the plunger rod is so long that the elastomeric stoppercan be compressed when it contacts the distal end of the chamber in thebarrel. If the user compresses the stopper and then relieves thepressure on the plunger rod flange the stopper will expand back to itsnormal size drawing liquid from the catheter into the syringe barrel.This is undesirable since this event can cause blood to undesirablyenter the catheter at the catheter distal end.

A syringe assembly 55 of the present invention preferably includes asyringe barrel 56 having an elongated body 57 defining a chamber 58 forretaining fluid. The syringe barrel includes an open proximal end 59having a barrel flange 61, a distal end 62 and a frusto-conically shapedtip 64 extending from the distal end and having a tip passageway 65therethrough in fluid communication with the chamber. The insidediameter A of the chamber is at least 13.5 mm (0.53 inch). Chamber 58includes a distal end defined by distal chamber wall 68. The length ofthe chamber is illustrated as element C in FIG. 5 and is measuredapproximately between the distal chamber wall and the proximal end ofthe chamber. The chamber is the generally constant diameter of constantcross-section portion of the inside of the barrel. Although a widevariety of chamber lengths are within the purview of the presentinvention, the preferred embodiment has a chamber length C which is nomore than about 57 mm (2.25 inches) with a chamber length of no morethan about 44.5 mm (1.75 inches) to 38.1 mm (1.5 inches) being desirablefor many applications. A stopper 70 is in fluid-tight engagement insidethe barrel. An elongated plunger rod 73 having a distal end 75 and aproximal end 76 defining a longitudinal axis 74, extends proximally fromthe stopper through the open proximal end of the barrel. In thisembodiment, the plunger rod and the stopper are separate elements. Thestopper is preferably made of an elastomeric material selected from thegroup of natural rubber, synthetic rubber, thermoplastic elastomers orcombinations thereof. The plunger is preferably made of a rigidthermoplastic material. Plunger rod 73 includes a distally directedthreaded extension 74 which engages a threaded recess 71 in stopper 70.In this embodiment, the syringe may be assembled without the plunger rodfor purposes such as conserving space or reducing packaging material,and the plunger rod may be assembled to the stopper at the time of useby simply screwing the plunger rod into the stopper.

There are many ways to connect the stopper to a plunger rod includingsnap-fit structure, adhesives, welding and two-shot molding where astopper of one material is molded with a plunger rod of anothermaterial. The threaded arrangement described hereinabove is consideredexemplary of these many possibilities. It is also within the purview ofthe present invention to include a one-piece plunger rod and stopperassembly wherein the stopper and plunger rod are made of the samematerial.

The plunger rod also includes a plunger rod flange 77 at proximal end 76of the plunger rod. As will be explained in more detail hereinafter, itis preferred that flange 77 is shaped and positioned to limit the distalmotion of the plunger rod in the barrel by contacting the proximal endof the barrel rather than having the stroke of the plunger rod andstopper being limited by the stopper being compressed against distalchamber wall 68. Ideally, the flange should stop the forward motion ofthe stopper at the moment the distal face 72 of the stopper contactsdistal chamber wall 68. When there is a space between at least a portionof the distal end or distal face of the stopper and the distal wall ofthe barrel. Since manufacturing tolerances will vary, it will be up tothe manufacturer to choose whether there should be a gap between thestopper and the distal barrel wall or a slight stopper deflection whenthe plunger rod flange contacts the proximal end of the syringe barrel.In any event, it is not desirable to have excessive compression of thestopper which can, upon release of the plunger rod, draw blood into acatheter during a flush procedure.

A tip cap 80 is releasably connected to tip 28 sealing passageway 29. Itis preferred that the tip cap is formed of material selected from thegroup of thermoplastic material and elastomeric material withelastomeric material being preferred. The syringe assembly of thepresent invention may contain volumes of fluid from about 1 ml to 10 mlwherein in the preferred embodiment contains no more than 3.3 ml ofinjectable liquid 82 in the chamber. It is preferred that the injectableliquid be selected from the group consisting of saline flush solutionand heparin lock flush solution. These solutions are known in the artand readily available. An example of a saline flush solution is 0.9%Sodium Chloride USP. An example of a heparin lock flush solution is 0.9%Sodium Chloride with 100 USP units of Heparin Sodium per ml or 10 USPunits of Heparin Sodium per ml.

The materials for the syringe barrel, the tip cap and the stopper willhave to be chosen based not only on performance but on compatibilitywith the injectable liquid. In this preferred embodiment the syringeassembly is prefilled with injectable liquid. There may be a substantialamount of time between when the syringe assembly is filled and when thecontents of the syringe assembly are delivered. Accordingly, materialschosen for the syringe assembly may have to be stable under long termstorage.

The syringe assembly contains volume measuring indicia 83 on elongatedbody 57. The volume measuring indicia in the preferred embodiment showsvolumes up to 3.0 ml. However, since the syringe assembly is preferablyprefilled, the indicia may be limited to the exact amount of liquid inthe syringe, for example, 3.0 ml. An important feature of the presentinvention over the smaller diameter 3 ml prior art syringes is that thelarger diameter barrel provides a satisfactory area for printed orlabeled instructions or a description of the syringe contents.

Syringe assembly 55 can be used to flush catheters having I.V. sites ina manner similar to that described above for the prior art syringe.However, there are several major differences and advantages in using thesyringe assembly of the present invention. To use syringe assembly 55 ina flushing procedure, the user first removes the tip cap and applies aneedle assembly such as needle assembly 37 or a needle assembly having ablunt tip if the I.V. site has a pre-slit septum. Also, in I.V. siteshaving a valve, the user removes the tip cap and applies the syringedirectly to the valve. Syringe assembly 55 is illustrated in FIG. 6 asbeing used with needle assembly 37 and I.V. site 50. When the needleassembly is applied to the syringe barrel the assembled unit is moved inposition so that sharp tip 43 of the needle will penetrate septum 53 andenter hollow internal conduit 52 of housing 51.

The user now advances the plunger rod in the distal direction byapplying digital pressure to flange 77 to expel the contents of thesyringe into and through the catheter. A major advantage of the syringeassembly of the present invention is that the fluid pressure will beonly about one-third of the fluid pressure if a prior art 3 ml syringewere being used with the same force being applied to the plunger rod.The reduced pressure makes it easier for the user to determine if thecatheter is open and reduces the possibility of dislodging a clot orrupturing the catheter. Also, if larger volume syringes having the samediameter are used, the general feel of the syringe and the techniquewill remain consistent from syringe to syringe so that the feel and thetouch and the forces applied in flushing the catheter with the 3 mlsyringe of the present invention are the same as a 10 ml syringe havingthe same diameter.

A further advantage of the present invention, as best illustrated inFIGS. 6 and 7 is that the distal motion of the plunger rod is limited byflange 77 contacting distal end 59 of the barrel.

As previously mentioned, it is important to maintain a positive pressurein the intravenous line to prevent blood reflux into the catheter lumen.This can be conveniently achieved by partial withdrawal of the cannulafrom the septum during the injection of the final volume of injectableliquid. It is an important advantage of the present invention that itmaintains positive pressure in the line for two reasons. First, at theend of the fluid delivery plunger rod flange 77 is in contact with theproximal end of the syringe barrel and is not sticking out or spacedfrom the proximal end of the barrel as with the prior art syringe asillustrated in FIG. 1. Therefore, inadvertent or accidental movement ofthe plunger rod in a proximal direction, to create negative pressure inthe line, is avoided. In this preferred embodiment, the plunger rodflange 77 is sized and shaped to be smaller than barrel flange 61 in alldimensions measured radially from the longitudinal axis of the plungerrod. Accordingly, the plunger rod flange cannot be pulled back at theend of its stroke. Many prior art syringes contain a round plunger rodflange and an oblong or non-circular barrel flange so that even when theplunger rod flange is close to the barrel flange it still is larger in aradial direction for easy movement of the plunger rod in a proximaldirection with respect to the barrel. However, since the syringeassembly of the present invention is preferably prefilled there is noneed for having such ready access to the plunger rod flange.

Secondly, as can be seen in FIG. 7 when plunger rod flange 77 is incontact with proximal end 56 of the syringe barrel distal end or distalface 72 of the stopper is spaced from distal chamber wall 68 of thesyringe barrel. This configuration prevents the stopper from beingexcessively compressed against distal chamber wall 68. If the plungerrod is long enough to allow substantial compression of the stopperrelease of the force on the plunger rod will allow the stopper to expandand possibly pull fluid back from the catheter and allow blood to enterthe catheter tip. In this embodiment it is preferred that the effectivelength B of the stopper and the plunger rod is measured from the distalside of plunger rod flange 77 to distal end 72 of the stopper shall be51 mm (2.0 inch) or less.

Accordingly, the syringe assembly of the present invention has two majoradvantages over prior art syringes in that its large diameter, neverbefore available in a 3 ml syringe, reduces the pressures associatedwith flushing an I.V. catheter thereby making it easier for the user todetect a clot and less likely that the fluid pressures will damage thecatheter. Further, refluxing is prevented or substantially minimized byhaving a plunger rod flange which limits the stroke of the plunger rodand the stopper assembly so that the stopper cannot be substantiallycompressed on the distal syringe barrel wall which may cause refluxingof fluid and blood into the catheter.

Syringe assembly 55 may be provided in a tearable or frangible packagewhich provides a tamper evident barrier surrounding the syringeassembly. Materials such as paper coated paper, plastic film, foil andcombinations thereof can be used for such purposes. Tearing of thepackage may be evidence that the syringe has been used or tampered with.Syringe assembly 55 may also be provided in a package which provides asterile barrier surrounding the syringe assembly. A package whichconstitutes a sterile barrier which provides substantial resistance tothe passage of microorganisms can be made of many known materials suchas paper, coated paper, plastic film, foil, non-woven materials andcombinations thereof. If the package is made of appropriate tearable orfrangible materials it can function as a sterile barrier and as a tamperevident package. In making the packaged syringe assembly, syringeassembly 55 can be sterilized after filling and placed in the package orplaced in the package and sterilized or sterilized, placed in thepackage and sterilized a second time.

In addition to the preferred syringe assembly 55 of the presentinvention, as illustrated in FIG. 8, other embodiments of the presentinvention include a syringe assembly 85 having a capacity of about 5 mland a syringe assembly 95 having a capacity of about 10 ml. All threesyringe assemblies have an inside diameter of at least about 13.5 mm(0.53 inch).

Referring to FIG. 9, a catheter flush kit comprises a first syringeassembly 100 and a second syringe assembly 101. Each of the syringeassemblies includes a syringe barrel (102, 103) having an elongated body(104, 105) defining a chamber 106, 107 for retaining fluid. Each syringebarrel includes an open proximal end 110, 111, a distal end 112, 113 anda frusto-conically shaped tip extending from the distal end and having atip passageway 116 and 117, therethrough in fluid communication withchambers 106 and 107. Each chamber has an inside diameter of at least13.5 mm (0.53 inch) and a distal end defined by a distal wall 118 and119 through which the passageways pass. A stopper 120 and 121 is influid-tight engagement inside each barrel. Elongated plunger rods 122,123 define a longitudinal axis and extend proximally from the stoppersthrough the open ends of the barrels. Flanges 124 and 125 are positionedat the proximal ends of plunger rods 122 and 123. A tip cap 126 and 127seals the passageway of each syringe. First syringe 100 has no more thanabout 3.3 ml of a first injectable liquid 130 in chamber 106. The secondsyringe assembly has no more than about 10 ml of a second injectableliquid 131 in chamber 107. The injectable liquids are selected from thegroup consisting of saline flush solution and heparin lock solution.Syringe assemblies 100 and 101 are contained in a package 132 whichpreferably provides a tamper evident barrier surrounding the syringeassemblies. The plunger rod flange in at least one of the syringeassemblies is shaped and positioned to limit the distal motion of theplunger rod in the barrel by contacting the proximal end of the barrel.

1. An I.V. flush syringe assembly comprising: a syringe barrel having anelongated body defining a chamber for retaining fluid, an open proximalend, a distal end and a frusto-conically shaped tip extending from saiddistal end having a tip passageway therethrough in fluid communicationwith said chamber, said chamber having an inside diameter of at least13.5 mm (0.53 inch), said chamber having a distal end defined by adistal wall through which said passageway passes, the length of saidchamber being no more than 57 mm (2.25 inches); a stopper in fluid-tightengagement inside said barrel; an elongated rigid plunger rod defining alongitudinal axis and extending proximally from said stopper throughsaid open proximal end of said barrel, a flange at a proximal end ofsaid plunger rod; a tip cap releasably connected to said tip for sealingsaid passageway; and flush solution in said chamber, wherein the fluidpressure in the flush solution injected through said passageway whenforce is applied to the plunger rod is about one-third of the fluidpressure in a flush solution injected through a passageway of a syringebarrel having an inside diameter of less than 13.5 mm when the sameforce is applied to the plunger rod.
 2. The syringe assembly of claim 1,wherein the length of said chamber is less than about 57 mm (2.25inches).
 3. The syringe assembly of claim 2, wherein the length of saidchamber is in the range of 38.1 mm (1.5 inches) to 44.5 mm (1.75inches).
 4. The syringe assembly of claim 1 wherein said chambercontains no more than 3.5 ml of flush solution.
 5. The syringe assemblyof claim 1 wherein said syringe assembly is contained in a package whichprovides a barrier surrounding the syringe assembly, the barrierselected from one of a tamper evident barrier and a sterile barrier. 6.The syringe assembly of claim 1 further including volume measuringindicia on said barrel.
 7. The syringe assembly of claim 6, wherein saidvolume measuring indicia indicates the stopper position for a chambervolume of about 3 ml.
 8. The syringe assembly of claim 1, wherein saidinside diameter of said chamber is approximately 14.5 mm (0.57 inch). 9.The syringe assembly of claim 1 wherein said plunger rod flange issmaller than said open proximal end of said barrel when measured in adirection perpendicular to said longitudinal axis so that said plungerrod flange does not extend radially beyond said barrel.
 10. The syringeassembly of claim 9 wherein said stopper and said plunger rod aredimensioned so that when said plunger rod flange contacts said proximalend of said barrel there is a space between at least a portion of thedistal end of said stopper and said distal wall of said barrel.
 11. Thesyringe assembly of claim 1 wherein said plunger rod includes a threadedextension projecting from a distal end of said plunger rod and saidstopper defines a threaded recess which engages with said threadedextension of said plunger rod.
 12. An I.V. flush syringe assemblycomprising: a syringe barrel having an elongated body defining a chamberfor retaining fluid, an open proximal end, a distal end and afrusto-conically shaped tip extending from said distal end having a tippassageway therethrough in fluid communication with said chamber, saidchamber having an inside diameter of at least 13.5 mm (0.53 inch), saidchamber having a distal end defined by a distal wall through which saidpassageway passes, the length of said chamber being no more than 57 mm(2.25 inches); a stopper in fluid-tight engagement inside said barrel;an elongated rigid plunger rod defining a longitudinal axis andextending proximally from said stopper through said open proximal end ofsaid barrel, a flange at a proximal end of said plunger rod; a tip capreleasably connected to said tip for sealing said passageway; and flushsolution in said chamber in an amount less than 10 ml, wherein the fluidpressure in the flush solution injected through said passageway whenforce is applied to the plunger rod is substantially the same as thefluid pressure in a flush solution in an amount of 10 ml or greaterinjected through said passageway when the same force is applied to theplunger rod.
 13. The syringe assembly of claim 12, wherein the syringebarrel comprises a barrel flange with a first dimension, the flange ofthe plunger rod having a second dimension that is smaller than the firstdimension.
 14. The syringe assembly of claim 12, wherein the flange ofthe plunger rod does not limit motion of the plunger rod in the barrelin a distal direction.
 15. The syringe assembly of claim 12, wherein theplunger rod is attached to the stopper and the length of the plunger rodand the stopper is 51 mm (2.0 inches) or less.
 16. The syringe assemblyof claim 12, wherein the flush solution is present in an amount in therange from about 1 ml to about 10 ml.
 17. The syringe assembly of claim12, wherein the flush solution is present in an amount of 3.3 ml orless.
 18. A syringe barrel having an elongated body defining a chamberfor retaining fluid, an open proximal end, a distal end and afrusto-conically shaped tip extending from said distal end having a tippassageway therethrough in fluid communication with said chamber, saidchamber having an inside diameter of at least 13.5 mm (0.53 inch), saidchamber having a distal end defined by a distal wall through which saidpassageway passes, the length of said chamber being no more than 57 mm(2.25 inches), the chamber containing flush solution in an amount lessthan 10 ml.
 19. The syringe barrel of claim 18, wherein said syringebarrel is contained in a package which provides a barrier surroundingthe syringe assembly, the barrier selected form one of a tamper evidentbarrier and a sterile barrier.
 20. The syringe assembly barrel of claim18, further comprising volume measuring indicial.